Heat Exchanger Testing – Part 2





Welcome to this lecture in the previous class we were talking about the steady state technique for measuring the heat transfer coefficient or the j-factor coefficient for the plate fin type of heat exchangers. And then we had seen that the steady-state technique, in the steady state technique we have the condensing steam and the air is getting heated up and turning the heat transfer between the fluid and condensing state and air dates and it picks up the kids from the condensing steel and the currency exchange get condensed and in fact made two examples that the heat transfer coefficient the temperature on the inside I will have a constant what temperature it will be maintained at the condensing steam temperature weather the air will be getting heater.com it's in the temperature toI feel that the CEO of the heat capacity weight ratio is cheer up because the condensing stamens are having a very high heat transfer coefficient and we had this year because to chino and the heat capacity basically is very high for the condensing scheme so we have this high because of that one we have this year equals 20 and we have a constant temperature pork on the same side now that is getting heated up from the t into the exit so now we in this condition what we do is we measure the temperature of temperature of air we measured the floor right up there and be able to calculate the starting temperature for Latinos depending on the pressure of the saturated steam and exit and inlet and exit of the air temperature is measured so we have an idea about the issue and once we know that you basically this is why see me this email is nothing but the air capacity this email is known and we know that until that is equals to n cubed is it was basically this uniform this relation we have already calculated from the measured value of the inlet and exit temperature and the temperature temperature so we can understand that we have the knowledge of you so once we know the way as we have seen in the previous like that because of stuff like that we have seen that this is the one part this one by ear part is related to the only transportation it is also known as resistance but already have an estimate of this away and now we would be able to calculate the sunroom heater aspatal patients that we have put the test services on this site so this is how we measure the transfer coefficient in the pattern type of heat exchangers in the form of the heat exchanger and moreover in the same they will also calculate the from the inlet and exit pressure drop with major and the from this differential pressure measurement we can correlate it to the different classes here we have the quote this is the code fraction part and then we have the entry and the exit lost as we discussed earlier during the celebration type of heat exchanger pressure drop calculations and this is that lost their will find that is going through our dog and that she’s also giving some kind of special class and that is also his second but these parameters will be generally very small as compared to this for pressure drop so these parameters are generally known as we have the loan value of the King and Casey and we know how to estimate that and we have the pasta cyclone and the pressure factor of the rectangular duct offand from there we will be able to estimate all these parameters and we can now celebrate this fraction practice corresponding to the pressure drop our aim in the way we have the test surfaces so basically we measure the pressure drop and then from there we calculate the friction factors using this relation if someone wants that you don’t turn it that particular see you know we can easily look like this time make one can just concentrate on this part and one can find out the friction factor from the pressure drop calculation but someone is looking for an accurate measurement of the friction factor that one has to take care of all these are the parameters is given in the equation we will beand the best surfaces are there on the air side and on the same side so we can understand that we have two circuits as well as generating the field and the other part is there and this is as low pass and we had a blowout on the side so we have it flow control valve here and this is a letter application system to monitor the temperature and pressure at the different points so here we will first of all separated tough out into three components one in their side one is the same side and separately when it look into this particular design of this election year for this to understand this state transfer technique this is the closest we have the against Belmont then this section here we have the professional reputation this is generally in case of let me type it in there depending on the most of the time you will find that perception is a rectangular cross-section and whistleblowers and this transition from Bangalore to circular is generally done at the entry of the lord and we have at the end of the blower’s we have no control to test it and the different number so this is what about the air flow system and the aircraft that has been usedpressure drop the pressure head available with the blower and it’s the motor RPM and powerless 75hp so basically what it is and what it’s called their drug configuration depending on the best setup and the idea is that you need that will dictate the discount or the size of the blower will be basically governed by the type of heat exchanger services we’re going to test them so here we have taken this kind of dimensions this is the flow statement that has been used in this particular so straight section this is the exchange of what is the height and distance for a flow control valve which has been placed in this position now go to the steam system system system is basically I win the lottery system we have yous done on my vehicle fired boiler it is a package type of Violet which gives nearly about 480 kg of rice cream and at a pressure of 15 kg per centimetre Square so when we want to take it to the heater recirculation but it’s very difficult to maintain it and going through this still get condensed and it may create some kind of superstar in this on that side so that’s why it’s allowed basically this is to tell you that this is the method used by kaizen London and we have adopted thatwe maintain the steam at the nearly about 4° supercheap is maintained at this point and it is the nearly about 1.4 21.5 bus stop here we have the steam at 15 bath precious nearly and go from there we will be reducing at 21.5 bus but if he wants to do it in a single stage you know that that would be very large degree of super get me don’t be able to control it at this point so what we doing that we reduce it in two stages one we know by the time it comes from this wireless police find no to the first of all ages and all it will be available at a pressure of 10 over so from 10 but we did use it to 3.5 bar and that will give you some degree of superhit and that stupid it is in the movie in order to remove dust superhit we make sex with the water so this one as wellsocial changes that will be lost and along with that there will be concessions so mostly will be responding to the situation temperature situation pressure of 1.5 that is used in this process is about 326 times of the parts and the system is used to because we do not want any accumulation of the steam on the condensate on the inside is any condensation process on that one will reduce the effort is getting accumulated distance getting condensed and recondense if compensation if it is accumulating on the inside that will reduce the heat transfer coefficient so we want the drainage of that the experts are convinced that all the contents and that’s why we use the existing and that it is time will take care or remove the condensate from that it is from the test channels of the on the scheme since this condensate is there again collected and then we measured it and submit and collect this contest that gives you an idea about the energy balance and this came out this is about the destruction of the steam system and then we have this makes us special attention because these exchanges activity designed carefully otherwise that’s going to give you a loan year’s results and the recommendation is that the issue is it should be nearly ca-123 and there is a reason for that if you’re going to use a very high and two exchanges we can expect that you know that ain’t true relation we have known as the one by 1 – Epsilon and that’s enough that it’s alive for the key it is that steers and the inductive research is this is clean and the city so this is coming at 10 and it is moving out at the house and this dust inside temperature setting now if it is such that protections into is very high we will end up with that you know that is -3 hours ahead is notand that the probability of error will be you know it can be shown that this error estimation will be much more so we designed the exchanges so that the into dementia within 1 to 3 and they lost him to convince the ratio is as I told you that it has to be nearly ca326 so the load capacity or it has already been decided depending on the Reynolds number and the pressure head available with that kind of blood and out of that you’re available pressure hate the only a part of this one will be available for this election year old this is the only heat exchanger for this is the length of the exchange rate for the pick up the sides in this is this is the face is that the thing which we are going to test do that the feng shui which we will be testing and the pressure drops for that he text me a photo of length l70% of the pressure cape available with this blow-up will be allocated for The corporation drop and let’s top it will be true that our list of lost right now then talked and etc etc but that will be consumed by that remaining part and we have him that 480 kg of dry skin and depending on this assumption are we have calculated the heat exchanger design has been done so starting with the NQ first calculator in the from this relation we calculate the exact temperature and from there we calculate the mean values and the innovation lab in temperature from there we already know the field details from there we can calculate the hydraulic diameter etc and we can steam at the pressure drops so once we know the pressure dropstop the heat transfer coefficient and the pressure drop pass the test services and from there we can check whether they said that I don’t know somebody or whether you know it is conforming to our product or you know whether it is that time maintaining that into consideration within three to six and accordingly will be finalizing the length of the heat exchanger so once we know the heat exchanger length we can test it and put it in the test section this is the pictorial view of the test setup this is the boiler and then we have this is the boiler visit the different pressure I’m introducing station pressure-reducing station 12 and then we have this still coming like this this is that heat exchanger the steam is going like this and getting condensed and then it will be following this month there is another test section decision remove that parton this side and then you know there will be flowing this is an induced iPhone so we have the slower and this is the father and the motor is on the backside suggested that pictorials of the day started so here’s some of the instrument the part I meant this is basically a pic a single fare to platinum resistance thermometer and we have measured the inlet temperature at a particular point but for the measurement of the temperature we have to measure it at different locations because we expect a new non-informative in the temperature in Chennai in the effect of the structure that's about the measurement part then we have also measure the flooring at different locations I mean at the entry of thecalibration of the pacesetter what we need best surface for fridge the heat transfer coefficient of the pressure drop is not initially what we did is theinitially what we did is the new we calculated the friction factor and this is the case status has been tested by the fable London and we had the data for the kids and London and to test that we have our test setup correctly build we have measured the pressure drop and different time and what is important for any test or the measurements of thermal measurement thermal hydraulic measurement is the repeatability test so we have done these experiments time and again and we have calculated or have seen that it is conforming to the values given by the kaizer London so this is basically the whole test of this is where we didn’t use the steam only the air was flown to the Hilux injector service so this is how we have measured the in the friction factor and then in presence ofwe can understand that the defective and friction factor at very closely related are there I'm in there almost following the results given by the case in London so this collaboration will be able to eliminate what is called the systematic error any any any any experimentsstop this is Brenda my destination and this is the type of expression that we use for calculation of the random errors this is if there are a number of zn number of parameters X1 X2 explained that we had the error associated with that measurement will be accepted and the US will have a component in this is the Delta X1 associated the error associated with the X1 and this is Delta h to associated with X2 and so on and it keeps on adding and the Arabs are additive so the total error associated with this measurement will be tilted comprising of all the individual errors of measurement but another estimate of this depression it is given by this relation before so this is how we estimate there are the random error associated with any kind of payment so when we talk about the Mini channel it’s slightly different you may be expecting a similar kind of test setup but here we go for a power supply and we heat it up from the bottom and it’s unlikely they will send the Steam in this one because the sea can understand The dimension of the surfaces and the services are very small in science this is about .25 mm channel and here we do a different type of test that we calculate the Florida or are we simulate thewhen allow the water to flowing through the small channels and we believe the pressure drop across this channel and then we also put some known amount of heat through the power supply and then we estimate the heat transfer and accordingly we calculate the heat transfer and the pressure drop for these channels so this is the kind of protest set up interviews for the samples ordered and this is the type of experimental setup where we had the savings farms data activation system then this is the power supply and like that so in case of a transfer of a similar type of experimental setup is used but still vary from time to time and he is just too inhabitants of this taste better this is the rectangular section so here it is it is heated up from the top and the bottom and this is where we had the aluminium metal formed within it and we measure the it is supposed to be covered up know when it is in the it’d condition but for the video recording we have removed that discovered enter their maintain that particular temperature and the electrically heated up and this is the flow measurement device it is an inline flow metre and it is measuring the product and you will find will they show us their entry and this is the blood the air enters from this side and then it flows through this section this section and then it finally comes out like this suggests that the technician and thenamazing that this is a setup where we measure the heat transfer passport effectiveness so he’ll also put the water flowing through this one we allow water to flow through this channel then we put either sit in it and then you know this is the other fluid at the same place but with 30% temperature and then you know it is flowing like this in a closed loop this is that cold fluid at this is the efficiency and we’re putting heat and from measurement of all these temperatures we will be able to calculate the efficiency or overall efficiency of this heat exchanger. So this is about the test set up of the heat exchanger. Thank you for your attention.